Arch-shaped centralizing returnable large-range rotary fishing spear and using method thereof

Abstract

A spear rod is connected to the lower end of a top connector, a milling guide cone is connected to the lower end of the spear rod, the spear rod is divided into a small-diameter section at the upper end and a large-diameter section at the lower end, a slip limiting step is formed at the transition position, a split type slip is connected to the small-diameter section in a sleeving mode, and the split type slip is connected to the large-diameter section in a sleeving mode. An inner hole of the lower end of the split type slip forms an inner taper expansion slope, the large-diameter section is sleeved with a slip cone, the slip cone is provided with a shear pin, the shear pin extends into the shear pin fixing groove, the left side of the slip cone is an outer taper slope, and the upper end of the split type slip is connected with the sliding sleeve through an arch-shaped centralizer. The slip can be automatically centered when entering the inner diameter of a falling object through arch-shaped centralizing, the multi-petal type slip can be matched with the inner diameter of the falling object within the floating range of 1-20 mm, the multi-petal type slip can freely rotate so that the inner diameter of an irregular well hole and the inner diameter of a deformed falling object can be milled and trimmed in the fishing process, and it is guaranteed that the split type slip can smoothly enter the inner diameter of the falling object; the shear pin can be disengaged without reversing the drilling tool.

Description

Technical Field

[0001] This invention relates to a bow-shaped, retractable, wide-range rotating retrieval spear and its method of use, belonging to the technical field of oil and gas well retrieval equipment. Background Technology

[0002] In oil and gas drilling operations, due to long-term use, the drill string material is prone to fatigue failure, inevitably leading to breakage. Fishing becomes a common downhole operation, and the fishing spear is the core tool for achieving this. Existing fishing spears generally suffer from four major technical defects: First, the slips have a narrow compatibility range. A single-specification fishing spear slip can only accommodate objects with a fixed inner diameter, resulting in a limited fishing range. For objects with fluctuating inner diameters, slips need to be changed multiple times, leading to low operational efficiency. Second, the slips cannot smoothly enter irregular or deformed objects. Third, the slips are prone to eccentricity when entering the object's inner hole, especially when the wellbore is irregular or the object is tilted. This makes it difficult for the fishing spear to enter the object's inner hole centrally, easily leading to slip wear, insecure grip, and even secondary stuck drill bit accidents. Fourth, the slips are difficult to remove after a secondary stuck drill bit encounter. Traditional retractable fishing spears require reversing the drill string to dislodge the slip. In complex well conditions, reversing the drill string can easily cause fatigue damage, and the success rate of dislodgement is low.

[0003] To address the aforementioned issues, developing a retrieval spear that is adaptable to large-scale retrieval, can correct irregular and deformed inner holes of fallen objects, automatically centers and straightens itself, and can be unloaded without reversing is key to improving the efficiency and safety of downhole retrieval operations. Summary of the Invention

[0004] The purpose of this invention is to provide a bow-shaped, retractable, wide-range rotating retrieval spear and its method of use. It solves the technical problems of existing retrieval spears, such as narrow slip fit, inability of the slips to smoothly enter irregular and deformed object bores, easy eccentricity of the slips when entering the object bore, and difficulty in retracting the slips after jamming. It is suitable for retrieval operations of tubular objects such as tubing, drill pipe, and packer center tubes in oil and gas wells, and is especially suitable for complex conditions such as irregular wellbores, irregular and deformed object bores, and object eccentricity or large fluctuations in inner diameter.

[0005] The technical solution of this invention: A bow-shaped, retractable, wide-range rotating retrieval spear, comprising a top connector, a spear shaft connected to the lower end of the top connector, and a milled guide cone connected to the lower end of the spear shaft. The inner holes of the top connector, the spear shaft, and the milled guide cone are interconnected to form an axial flow channel. The middle part of the spear shaft has two smooth passages with different outer diameters, and a slip limiting step is formed at the transition position. A segmented slip is movably fitted on the upper small-diameter section of the spear shaft, and the lower end of the segmented slip has an inner hole that gradually opens downwards. The spear shaft has a large inner tapered expansion ramp. A slip cone is movably fitted on the large diameter section of the spear shaft. The slip cone is equipped with a shear pin. The bottom end of the shear pin extends into the shear pin fixing groove on the outer circumference of the spear shaft. The left side of the slip cone forms an outer tapered ramp with a gradually increasing downward dimension. The upper end of the split slip is connected to an arched stabilizer. The upper end of the arched stabilizer is fixedly connected to a sliding sleeve movably fitted on the spear shaft. The split slip can slide freely along the smaller outer diameter surface of the spear shaft until it is limited at the slip limiting step.

[0006] In the aforementioned bow-shaped retractable large-range rotating salvage spear, the bow-shaped stabilizer is formed by multiple bow-shaped elastic stabilizer plates evenly distributed circumferentially, and each bow-shaped elastic stabilizer plate is fixed at both ends to the sliding sleeve and the segmented slip plate by fixing screws.

[0007] In the aforementioned bow-shaped, retractable, wide-range rotating retrieval spear, the upper and lower ends of the spear shaft are respectively threaded into the threaded countersunk holes at the lower end of the top connector and the upper end of the milled guide cone, and are locked together by anti-drop pins.

[0008] In the aforementioned bow-shaped, retractable, wide-range rotating retrieval spear, a carbide milling head is welded to the lower end surface of the milling guide cone, and a flow channel groove is provided on the outer circle.

[0009] In the aforementioned bow-shaped, retractable, wide-range rotating salvage spear, the upper inner hole of the top connector is provided with a connecting thread.

[0010] A method for using a bow-shaped, retractable, large-range rotating retrieval spear: During the rotation and lowering of the retrieval spear, a milled guide cone is used to adjust the irregular and deformed inner hole of the object, guiding the segmented slips into the inner hole of the object. When the spear shaft rotates, it does not cause the segmented slips and their connected components to rotate together. The bow-shaped centering mechanism enables the segmented slips to adaptively center themselves. Under the action of the elastic deformation force of the bow-shaped centering mechanism, the segmented slips and the inner hole of the object form a whole through frictional resistance. When the drill bit is lifted and the spear shaft moves upward, the inner tapered expansion ramp and the outer tapered ramp cooperate to expand the outer diameter of the segmented slips, thereby achieving the retrieval of the object from the inner hole.

[0011] When the upward movement encounters a jam, increase the upward force to cut off the shear pin. The split-type slip and the slip cone descend without restraint. The split-type slip descends to the slip limit step and is then limited. The slip cone continues to descend without restraint. The inner tapered expansion slope loses its restraint, allowing the outer diameter of the split-type slip to return to its original state, thus releasing the object from the inner hole.

[0012] The beneficial effects of the present invention: Compared with the prior art, the bow-shaped, retractable, wide-range rotating retrieval spear of the present invention has the following advantages:

[0013] 1. This invention achieves automatic centering of the retrieval spear slips when they enter the inner hole of the object, by connecting the bow-shaped centering mechanism and the segmented slips and sliding sleeves with fixing screws to form an integral inner diameter that is aligned with the smooth central diameter of the expansion mandrel. In addition, the bow-shaped centering mechanism has multiple sets of elastic plates on the outside that are pre-pressed outward and adaptively contracted. This avoids eccentricity and wear, improves gripping stability, and reduces the risk of secondary stuck drill bits.

[0014] 2. Conventional retrieval tools utilize slip deformation to provide initial frictional resistance with the inner hole of the fallen object, resulting in a retrieval range of only 1-3mm. This invention, however, provides initial frictional resistance through an arc-shaped straightening deformation, extending the retrieval range to 20mm. It is suitable for large-diameter floating pipes, eliminating the need for frequent tool changes and significantly improving operational efficiency.

[0015] 3. The split-type chuck and rotatable spear rod design, along with the carbide milling head design on the end of the guide cone, ensure that irregular or deformed inner holes of the fallen object can be adjusted during the retrieval process to meet retrieval requirements.

[0016] 4. The "shear pin" structure eliminates the need to reverse the drill string when stuck. Simply increase the preset lifting force to dislodge the stuck part. This makes the operation convenient, protects the drill string from fatigue damage, and greatly improves the safety of downhole fishing operations.

[0017] 5. The through-flow design of the built-in axial flow channel ensures smooth circulation of drilling fluid, carries away cuttings, prevents jamming, and further improves the operational reliability of the tool.

[0018] In summary, this invention achieves automatic centering of the slips when they enter the inner hole of the object through an arch-shaped centering structure; the multi-lobed slips are suitable for objects with an inner diameter ranging from 1 to 20 mm; the rotatable design of the lobed slips and the spear rod allows for milling and trimming of irregular wellbores, irregular and deformed object inner holes during the retrieval process, ensuring smooth entry of the lobed slips into the object's inner hole; the removable "shear pin" structure allows for disengagement without reversing the drill string, significantly improving retrieval efficiency and operational safety under complex well conditions, and is suitable for retrieval operations of various types of pipe objects, such as tubing, drill pipe, and packer center tube. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention.

[0020] Reference numerals: 1-Top connector, 2-Spear rod, 3-Milling guide cone, 4-Split-type slip, 5-Inner taper expansion ramp, 6-Slip cone, 7-Shear pin, 8-Shear pin fixing groove, 9-Outer taper ramp, 10-Arch-shaped straightener, 11-Sliding sleeve, 12-Slip limiting step, 13-Fixing screw, 14-Anti-drop pin, 15-Carbide milling head, 16-Flow channel groove. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0022] An embodiment of the present invention: A bow-shaped, retractable, wide-range rotating retrieval spear includes a top connector 1, a spear shaft 2 fixedly connected to the lower end of the top connector 1, and a milling guide cone 3 fixedly connected to the lower end of the spear shaft 2. The inner holes of the top connector 1, the spear shaft 2, and the milling guide cone 3 are interconnected to form an axial flow channel, which is used to circulate drilling fluid and clean debris from the top of fallen objects. The middle part of the spear shaft 2 has two smooth passages with different outer diameters, wherein the upper section is a smaller diameter section and the lower section is a larger diameter section. A slip limiting step 12 is formed at the transition position between the larger diameter section and the smaller diameter section. A split-type slip 4 is movably fitted onto the upper small-diameter section of the spear shaft 2. The lower end of the split-type slip 4 forms an inner tapered expansion ramp 5 with a gradually increasing downward opening. A slip cone 6 is movably fitted onto the large-diameter section of the spear shaft 2. The slip cone 6 is equipped with a shear pin 7. The bottom end of the shear pin 7 passes through the slip cone 6 and extends into a shear pin fixing groove 8 on the outer circumference of the spear shaft 2, thereby limiting and fixing the slip cone 6. The left side of the slip cone 6 forms an outer tapered ramp 9 with a gradually increasing downward size. This outer tapered ramp 9 is used to cooperate with the inner tapered expansion ramp 5 of the split-type slip 4. When the two come into contact and squeeze each other, the split-type slip 4 is expanded, increasing its outer diameter, thereby grabbing the falling object. Conversely, when the two separate, the split-type slip 4 returns to its original outer diameter. The upper end of the split-type slip 4 is fixedly connected to an arc-shaped stabilizer 10, and the upper end of the arc-shaped stabilizer 10 is fixedly connected to a sliding sleeve 11 that is movably sleeved on the spear shaft 2. The split-type slip 4 can slide freely along the smaller outer diameter surface of the spear shaft 2 until its upper end moves to the slip limiting step 12 and is limited.

[0023] The bow-shaped straightener 10 is formed by multiple bow-shaped elastic straightener plates evenly distributed circumferentially. Each bow-shaped elastic straightener plate is fixed at both ends to the sliding sleeve 11 and the segmented collet 4 by fixing screws 13.

[0024] The upper and lower ends of the spear shaft 2 are respectively threaded into the threaded countersunk holes at the lower end of the top connector 1 and the upper end of the milling guide cone 3, and are locked together by anti-drop pins 14. The threaded connection structure facilitates the assembly and disassembly of components, and the anti-drop pins 14 prevent the threaded connection from loosening and causing the components to separate and fall off. Furthermore, two steps are formed at the connection points between the two ends of the spear shaft 2 and the top connector 1 and the milling guide cone 3. These two steps respectively limit the movement of the sliding sleeve 11 and the clamping cone 6, preventing them from sliding off the spear shaft 2 during sliding.

[0025] The lower end surface of the milling guide cone 3 is welded with a carbide milling head 15, which can trim irregular or deformed inner holes of fallen objects to meet the requirements for retrieval. The outer circumference of the milling guide cone 3 is provided with a flow channel groove 16, which can facilitate the smooth discharge of grinding debris during the drilling fluid flow process.

[0026] The upper inner hole of the top connector 1 is provided with a connecting thread, which facilitates the connection of the upper drilling tool through the connecting thread.

[0027] This invention relates to a bow-shaped, retractable, wide-range rotating retrieval spear, designed to solve the technical problems of existing retrieval spears, such as narrow adaptability, difficulty in smoothly inserting the slips into irregular and deformed objects' inner holes, easy eccentricity of the slips when inserted into the object's inner hole, and difficulty in retracting when stuck. The main structure consists of a top connector 1, spear shaft 2, milled guide cone 3, split slips 4, slip cone body 6, shearing pin 7, bow-shaped centering 10, sliding sleeve 11, fixing screw 13, and anti-drop pin 14. The following is a detailed description of each component:

[0028] Top connector 1: The upper end is provided with a connecting thread for connecting the upper drill bit, and the lower end is fixedly connected to the upper end of the spear rod 2, with an internal axial flow channel.

[0029] Spear shank 2: The upper end connects to the top connector 1. The middle section consists of two smooth passages with different outer diameters. Between the two outer diameters is a slip limiting step 12. The segmented slip 4 can slide freely on the surface of its smaller outer diameter until it is limited at the slip limiting step 12 and cannot move further. The middle section of the larger outer diameter is provided with a shear pin fixing groove 8, which is used to fix the slip cone 6 here by shear pins 7. The lower end connects to the milling guide cone 3 and has an internal axial flow channel.

[0030] Milling guide cone 3: The end surface is welded with a carbide milling head 15, which can trim the irregular inner hole and deformed inner hole of the dropped object to meet the retrieval requirements. The outer circle is provided with a flow channel groove 16, which can realize the smooth discharge of grinding chips during the flow of drilling fluid during the grinding process. It has an internal axial flow channel.

[0031] Split-type slip 4: It is connected to the bow-shaped straightener 10 and the sliding sleeve 11 as a whole by fixing screw 13. It can move freely along the small smooth outer diameter surface of the middle part of the spear rod 2. The inner hole on the right side is provided with an inner tapered expansion slope 5, which cooperates with the outer tapered slope 9 corresponding to the slip cone 6 to realize the expansion of the outer diameter of the slip and retrieve the inner hole of the fallen object. The outer surface of the split-type slip 4 is provided with slip teeth with a 2-6 split structure. The outer surface of the slip teeth has high hardness characteristics and can easily bite into the inner hole surface of the fallen object.

[0032] The slip cone 6 is connected and fixed to the spear rod 2 in the middle by shear pin 7. The upper part is provided with an outer tapered inclined surface 9 that matches the corresponding position of the split slip 4 to ensure that the split slip 4 opens and closes, so as to retrieve and release the falling object. When there is no shear pin 7 to restrain it, the slip cone 6 can move freely along the larger smooth outer diameter surface of the middle part of the spear rod 2.

[0033] Shear pin 7: This is the breaking part that causes the retrieval spear to be released. Different release force values ​​can be obtained by selecting the number, material, and shear diameter.

[0034] Bow-shaped straightener 10: Multiple bow-shaped elastic straightener plates made of spring steel are connected to the split-type collet 4 and the sliding sleeve 11 on both sides by fixing screws 13, forming a sliding whole. The bow-shaped elastic straightener plates are evenly distributed in the circumference and protrude outward in an arc shape. The pre-compression opening angle of the bow-shaped elastic straightener plates is 15°–30°.

[0035] Sliding sleeve 11: Used to support the bow-shaped straightener 10, allowing it to move freely along the smooth passage in the middle of the spear shaft 2.

[0036] Anti-loose pin 14: Screw in after threaded connection is completed to prevent thread stripping.

[0037] The working principle of the bow-shaped, retractable, wide-range rotating retrieval spear of the present invention is as follows:

[0038] 1. Connect the top connector 1 to the upper drill string via the connecting thread provided at the upper end, and lower the retrieval spear into the bottom of the well along with the drill string;

[0039] 2. Drill down to the top of the debris, start the pump to circulate the drilling fluid through the built-in axial flow channels of the top connector 1, spear rod 2 and milling guide cone 3 to clean the debris on the top of the debris;

[0040] 3. During the pump circulation process, continue to use the method of rotating and lowering. The milling guide cone 3 can be used to repair the irregular inner hole and deformed inner hole of the falling object to meet the conditions for the slip introduction and guide the split slip 4 into the inner hole of the falling object.

[0041] 4. Due to the free rotation design between the split-type slip 4 and the spear rod 2, the rotational milling motion of the milling guide cone 3 driven by the spear rod 2 will not affect the external split-type slip 4 and the bow-shaped straightener 10.

[0042] 5. The inner diameter of the bow-shaped straightener 10, the split-type slip 4, and the sliding sleeve 11 connected by the fixing screw 13 is aligned with the smooth passage in the middle of the spear rod 2. The bow-shaped straightener 10 drives the split-type slip 4 to self-align. When the bow-shaped straightener 10 enters the inner hole of the falling object, it is in a compressed state.

[0043] 6. The bow-shaped straightener 10, the split-type slip 4, and the sliding sleeve 11 form a whole. Under the action of the elastic deformation force of the bow-shaped straightener 10, it forms a whole with the inner hole of the falling object through frictional resistance.

[0044] 7. Raise the drill bit, and the spear rod 2 moves upward. The inner tapered expansion ramp 5 on the right side of the split slip 4 cooperates with the outer tapered ramp 9 corresponding to the slip cone 6. As the slip cone 6 moves upward with the spear rod 2, its outer tapered ramp 9 squeezes the inner tapered expansion ramp 5 outward, causing the outer diameter of the split slip 4 to expand. The slip teeth on the outer surface of the slip bite into the inner hole of the fallen object, thus achieving the grabbing and retrieval of the fallen object from the inner hole.

[0045] 8. Continue lifting to retrieve the fallen object.

[0046] Exit: When encountering a jam during upward lifting, simply increase the upward lifting force. The slip cone 6 connected to the spear shaft 2 via the shear pin 7 is subjected to downward pressure from the split slip 4. When the force reaches the preset shearing force, the shear pin 7 is sheared, and the slip cone 6 descends without constraint. Simultaneously, the split slip 4 descends to the slip limiting step 12 and is limited, unable to move further downward. The slip cone 6 can still descend without constraint, and the inner tapered expansion slope 5 of the split slip 4 loses its constraint, causing the outer diameter of the split slip 4 to return to its original state, thus releasing the object from the inner hole.

Claims

1. A bow-shaped, retractable, wide-range rotating retrieval spear, characterized in that: It includes a top connector (1), a spear rod (2) connected to the lower end of the top connector (1), a milling guide cone (3) connected to the lower end of the spear rod (2), the inner holes of the top connector (1), the spear rod (2) and the milling guide cone (3) are interconnected to form an axial flow channel, the middle part of the spear rod (2) is a smooth passage with two different outer diameters, and a slip limiting step (12) is formed at the transition position, wherein a split slip (4) is movably sleeved on the upper small diameter section of the spear rod (2), and the lower end of the split slip (4) forms an inner tapered expansion slope (5) with a downward opening that gradually increases, and the large diameter section of the spear rod (2) The upper part is fitted with a slip cone (6), and the slip cone (6) is provided with a shear pin (7). The bottom end of the shear pin (7) extends into the shear pin fixing groove (8) on the outer periphery of the spear rod (2). The left side of the slip cone (6) forms an outer tapered slope (9) with a downwardly increasing dimension. The upper end of the split slip (4) is connected to an arc-shaped stabilizer (10). The upper end of the arc-shaped stabilizer (10) is fixedly connected to the sliding sleeve (11) that is fitted on the spear rod (2). The split slip (4) can slide freely along the smaller outer diameter surface of the spear rod (2) until it is limited at the slip limiting step (12).

2. The bow-shaped, retractable, wide-range rotating retrieval spear according to claim 1, characterized in that: The bow-shaped straightener (10) is formed by multiple bow-shaped elastic straightener plates evenly distributed along the circumference. Each bow-shaped elastic straightener plate is fixed at both ends to the sliding sleeve (11) and the split-type slip (4) by fixing screws (13).

3. The bow-shaped, retractable, wide-range rotating retrieval spear according to claim 1, characterized in that: The upper and lower ends of the spear shaft (2) are respectively screwed into the threaded countersunk holes at the lower end of the top connector (1) and the upper end of the milling guide cone (3), and are locked and fixed to each other by anti-drop pins (14).

4. The bow-shaped, retractable, wide-range rotating retrieval spear according to claim 1, characterized in that: The lower end surface of the milling guide cone (3) is welded with a carbide milling head (15), and the outer circle is provided with a flow channel groove (16).

5. The bow-shaped, retractable, wide-range rotating retrieval spear according to claim 1, characterized in that: The upper inner hole of the top connector (1) is provided with a connecting thread.

6. The method of using a bow-shaped, retractable, wide-range rotating salvage spear as described in any one of claims 1-5, characterized in that: During the rotation and lowering of the retrieval spear, the milling guide cone (3) trims the irregular and deformed inner hole of the falling object, and guides the split slip (4) into the inner hole of the falling object. When the spear rod (2) rotates, it does not drive the split slip (4) and its connected components to rotate together. Moreover, the bow-shaped straightener (10) drives the split slip (4) to self-align. Under the action of the elastic deformation force of the bow-shaped straightener (10), the split slip (4) and the inner hole of the falling object form a whole through frictional resistance. The drill bit is lifted and the spear rod moves upward. Through the cooperation of the inner tapered expansion inclined surface (5) and the outer tapered inclined surface (9), the outer diameter of the split slip (4) expands, realizing the retrieval of the inner hole of the falling object. When the upward movement encounters a jam, the upward force is increased, causing the shear pin (7) to be sheared. The split-type slip (4) and the slip cone (6) descend together without constraint. The split-type slip (4) descends to the slip limiting step (12) and is then limited. The slip cone (6) continues to descend without constraint. The inner tapered expansion slope (5) loses its constraint, causing the outer diameter of the split-type slip (4) to return to its original state, thus releasing the falling object from the inner hole.

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